File Permissions In Linux

 

permission	on a file	on a directory
r (read)	read file content (cat)	read directory content (ls)
w (write)	change file content (vi)	create file in directory (touch)
x (execute)	execute the file	enter the directory (cd)

 

File permissions for (-rw-rw-r--)
 
Syntax:
chmod <groupName>+<permissionName> <fileName> 
Example :-
chmod u+x file  < To add Permission >
chmod g-x file  < To remove Permission >

chmod u=rwx,g=rw,o=r file < To set explicit permissions >

 

Setting Octal Permissions
Octal permissions can also be set for the groups.

For example, to set r octal will be 4, to set w octal will be 2, to set x octal will be 1.

Octal Table:

binary	octal	permissions
000	0	---
001	1	--x
010	2	-w-
011	3	-wx
100	4	r--
101	5	r-x
110	6	rw-
111	7	rwx

1. 777 = rwxrwxrwx  
2. 765 = rwxrw-r-x  
3. 654 = rw-r-xr--  

 
Umask :- While creating a file or directory, by default a set of permissions are applied. These default permissions are viewed by umask command.
 
mkdir -m :- The 'mkdir -m' command can be used to set the mode.
Example :-
mkdir -m 777 new1  
mkdir -m 000 new2  
 
chmod 770 /ftpdata/florad3/nabk/h2h/hsbc/outfile
 
chmod g+s /ftpdata/florad3/nabk/h2h/hsbc/outfile - stick bits
 
chmod u+s /ftpdata/florad3/nabk/h2h/hsbc/outfile
 
set uid s = having excute permissions; S = do not have excute permissions

set guid